Poisonous Houseplants

Some houseplants are poisonous, warned University of Illinois Extension horticulture educator Rhonda Ferree. She stressed the importance of keeping them out of the reach of children and pets.

"There are three routes of exposure for poisoning: through the skin, inhaling through the nose, or eating," she explained.

Several houseplants, such as dumbcane (Dieffenbachia sp.), heartleaf philodendron (Philodendron cordata), anthurium, caladium, Swiss cheese plant (Monstera deliciosa), spathiphyllum, arrowhead vine (Syngonium podophyllum), and devil's ivy or pothos (Epipremnum aureum), contain calcium oxalate. Chewing on the tissue of these plants can cause painful and immediate swelling of the mouth and throat. Speech may be impeded, sometimes for several days.

Some plants, such as aloe and poinsettia, contain latex-type juices. When ingested, latex can irritate the large intestine and cause a cathartic (purging) reaction. The actual toxins in poinsettia are unknown, although it is no longer classified as extremely toxic. Reactions to poinsettia in humans include dermatitis, nausea, and vomiting.

Some holly berries (Ilex species) contain saponins. Chewing them can cause a burning sensation in the throat and gastronomical upset with vomiting and diarrhea. Jerusalem Cherry (Solanum pseudocapsicum) belongs to the same family as the deadly nightshade; its fruit and foliage should not be eaten.

Mistletoe (Phoradendron species) berries are also poisonous, causing vomiting, diarrhea, and moderate stomach and intestinal pain when eaten. In severe cases there may be labored breathing, dramatically lowered blood pressure, and heart failure.

"With stomach poisons, it is important to remember the dose makes the poison," Ferree said. "In other words, an amount that won't hurt a large dog might kill a small one."